Container-end tab and method of manufacturing same

Abstract

The product and method of manufacturing a tab having a rivet island window and adapted to be secured to a container end, including the steps of forming a first dimple at a first end position of the window and a second dimple at a second end position of the window, formed as depressed regions of metal residing outside the central plane of the metal. The method includes punching a first blank in the first dimple and a second blank in the second dimple, and subsequently bending the edge regions around the first and second blank to form a bend of the metal away from the central plane. The central region of the window is formed between and joining the blanks, and a rivet opening is formed, adapted to receive a rivet for staking the tab to a container end.

We claim: 
     
       1. The method of manufacturing a tab having a rivet island window and adapted to be secured to a container end, comprising the steps of; providing an elongated strip of plate metal having a thickness along a central plane;   forming a first dimple at a first end position of the window, and forming a second dimple at a second end position of the window;   punching a first blank within the first dimple and punching a second blank within the second dimple, said first and second blank each being an aperture having an edge region of dimple surrounding the blank   after forming said first blank and said second blank, bending said edge regions of the first and second dimple to form a bend of the metal away from the central plane.   
     
     
       2. The method of claim 1, wherein; the step of punching a first blank within the first dimple and punching a second blank within the second dimple further comprises forming apertures by a blanking punch having an incising diameter for removing a slug of metal in central area of the first and second dimple.   
     
     
       3. The method of claim 1, wherein the step of bending edge regions of the first and second dimple includes the steps of; piercing the first and second blank aperture with a tapered piercing tool and advancing said tapered tool to form a bend of metal in the edge region of each said dimple.   
     
     
       4. The method of claim 1, wherein, prior to the step of bending edge regions of the first and second dimple, further comprising the steps of; forming a central region of the window as an opening between the first and second dimple.   
     
     
       5. The method of claim 1, further comprising the steps of; forming a central region of the window by lancing the metal to form a lance separation of the metal in said central region between each of said blank apertures, the lance having a first edge area and a second edge area; and,   widening the lance separation by bending the metal immediately adjacent the first edge area of the lance away from said central plane to form a curl.   
     
     
       6. The method of claim 1, further comprising the steps of; forming a central region of the window by punching a curvilinear opening in the metal in the area between and joining the first and second blank apertures.   
     
     
       7. The method of claim 1 wherein the step of punching a first blank within the first dimple and punching a second blank within the second dimple includes forming apertures, each having a diameter approximately 0.035 to 0.045 inch. 
     
     
       8. A tab for a beverage container end made according to the method of claim 1. 
     
     
       9. The method of manufacturing a tab having a rivet island window and adapted to be secured to a container end, comprising the steps of; providing an elongated strip of plate metal having a thickness along a central plane;   forming a first dimple at a first end position of the window and a second dimple at a second end position of the window, said first and second dimple being a depressed region of metal residing outside the central plane;   punching a first blank in the first dimple and a second blank in the second dimple, each of said first and second blank being an aperture in a portion of the dimple and being formed by a blanking punch having an incising diameter for removing a slug of metal in central area of the first and second dimple, each dimple having an edge region surrounding the blank;   bending the edge regions of the first and second dimple to form a bend of the metal away from the central plane;   forming a central region of the window between and joining the first and second blank; and   punching a rivet opening in the rivet island, the rivet opening being adapted to receive a rivet for staking the tab to a container end.   
     
     
       10. The method of claim 9 wherein the step of bending the edge regions of said first and second dimples comprises; piercing the blanks with a piercing tool adapted to curl the edge regions and form widened openings of said blank.   
     
     
       11. The method of claim 9 further comprising the steps of; after the step of bending the edge regions, collapsing the bend of the edge regions to form a collar with an enhanced bend.   
     
     
       12. A tab for a beverage container end made according to the method of claim 9. 
     
     
       13. A tab for a beverage container end made according to the method of claim 11. 
     
     
       14. The method of claim 9 wherein the step of punching a first blank in the first dimple and a second blank in the second dimple includes removing a slug of metal having a diameter approximately 0.035 to 0.045 inch. 
     
     
       15. The method of manufacturing a tab having a rivet island window and adapted to be secured to a container end, comprising the steps of; providing an elongated strip of plate metal having a thickness along a central plane;   forming a first dimple at a first end position of the window, and forming a second dimple at a second end position of the window;   bending edge regions of the first and second dimple to form a bend of the metal away from the central plane;   after the step of bending the edge regions of the first and second dimple to form a bend of the metal, collapsing the bend of the edge regions to form a collar with an enhanced bend.   
     
     
       16. A tab for a beverage container end made according to the method of claim 15. 
     
     
       17. The method of manufacturing a tab having a rivet island window and adapted to be secured to a container end, comprising the steps of; providing an elongated strip of plate metal having a thickness along a central plane;   forming a first dimple at a first end position of the window and a second dimple at a second end position of the window, said first and second dimple being a depressed region of metal residing outside the central plane;   punching a first blank in the first dimple and a second blank in the second dimple, each of said first and second blank being an aperture in a portion of the dimple, each dimple having an edge region surrounding the blank;   bending the edge regions of the first and second dimple to form a bend of the metal away from the central plane;   forming a central region of the window between and joining the first and second blank;   punching a rivet opening in the rivet island, the rivet opening being adapted to receive a rivet for staking the tab to a container end; and,   after the step of bending the edge regions, collapsing the bend of the edge regions to form a collar with an enhanced bend.   
     
     
       18. The method of manufacturing a tab having a rivet island window and adapted to be secured to a container end, comprising the steps of; providing an elongated strip of plate metal having a thickness along a central plane;   forming a first dimple at a first end position of the window and a second dimple at a second end position of the window, said first and second dimple being a depressed region of metal residing outside the central plane;   punching a first blank in the first dimple and a second blank in the second dimple, each of said first and second blank being an aperture in a portion of the dimple, each dimple having an edge region surrounding the blank;   bending the edge regions of the first and second dimple to form a bend of the metal away from the central plane;   forming a central region of the window between and joining the first and second blank;   punching a rivet opening in the rivet island, the rivet opening being adapted to receive a rivet for staking the tab to a container end;   piercing the blanks with a piercing tool adapted to curl the edge regions and form widened openings of said blank; and,   after the step of bending the edge regions, collapsing the bend of the edge regions to form a collar with an enhanced bend.   
     
     
       19. A tab constructed of rigid material and adapted for attachment to a retained-tab container end, comprising; a hinge region generally disposed along a central plane and having a rivet island window and with a first end and a second end;   an edge region of each said first and second end of the window, each said edge region being curled away from the central plane to form a collar having a curl width in the range of 0.028 to 0.038 inch and a curl height in the range of 0.020 to 0.030 inch.   
     
     
       20. The tab of claim 13, wherein the collar is formed by curling a first and second dimple in the hinge region to form a bend of the metal away from the central plane and subsequently collapsing the bend of metal.